1. Field of the Invention
The present invention relates generally to rodless cylinders, and more particularly to a rodless cylinder in which a slider table and a cylinder body are made as small possible to minimize their occupied space, the cylinder body sufficiently supporting any load applied to the slide table and smoothly displacing the slide table in accordance with piston's reciprocating motion.
2. Prior Art
Many factories have recently used rodless cylinders for various workpiece transfer devices.
The rodless cylinder has an advantage over a roded cylinder in a short stroke length, thus, in a sufficiently small occupied area for a convenient fabrication. In addition, the rodless cylinder has an advantage over the roded cylinder in preventing dust from entering the cylinder, and consequently in positioning an object with high-precision.
Such rodless cylinders can be seen in U.S. Pat. Nos. 4,373,427 and German Patent No. 3,124,915. In particular, the rodless cylinder disclosed in the German Patent No. 3,124,915 includes a guide groove, provided between an outer circumferential surface of a cylinder tube and a top surface with a slit of the cylinder, and distinct guide means, provided at a leg member extending from both sides of the slide table to the cylinder tube, which are engaged with the guide groove. According to the German Patent No. 3,124,915, the guide means are engaged with each other so as to prevent the width of the slit from widening when the lateral force is applied.
However, according to the German Patent No. 3,124,915, it is necessary to extend the leg member from the slide table to a part more external than an outer slide surface of the cylinder tube, so as to hold the guide means. Therefore, when the lateral force is applied to the slide table and the guide means are engaged with each other, one end surface of the cylinder tube which defines the slit is compulsively approaches the other end surface of the cylinder tube which defines he other side slit; consequently the bore is wholly reduced so as to compulsively stop the piston. That is, the piston comes to stop in response to the lateral force, and thus the workpiece transfer operation unexpectedly stops, and the device is forced to be reluctantly made large due to the leg member.